1. Field of the Invention
The present invention relates to a head protecting airbag device. The airbag of the head protecting airbag device is folded and housed in the upper peripheral edge of a window in the interior side of a vehicle so that it may be expanded and inflated, when it admits an inflating gas, to cover the interior side of the window.
2. Description of the Related Art
Usually in the head protecting airbag device of this kind, an inflated airbag protects an occupant. Therefore, the head protecting airbag device is desired, when activated, to develop the airbag quickly. The construction of Unexamined Published Japanese Patent Application No. 2000-296753 is known as the head protecting airbag device which is constructed to expand the airbag quickly.
This head protecting airbag device is provided with two connection port portions at the upper edge side near the longitudinal middle of the airbag. These two connection port portions are opposed to each other in the longitudinal direction. The front and rear ends of the inflator are individually inserted into the two connection port portions so that the inflator is connected with the two connection port portions in a straight line.
When this airbag device is activated, the inflating gas is discharged from the two ends of the inflator in the axial direction of the inflator. Then, the inflating gas flows, through the two connection port portions of the airbag, in two directions, i.e., to the front side and to the rear side in the longitudinal direction of the vehicle so as to inflate the airbag.
In the head protecting airbag device of the prior art, however, the inflating gas, as discharged from the two ends of one inflator, is guided into the airbag through the two connection port portions. In other words, the airbag device of the prior art has two connection portions which connect the inflator and the connection port portions of the airbag. Therefore, in the head protecting airbag device of the prior art, the connecting work becomes complicated in the light of sealing properties, which caused a large number of working steps and a high cost.
Especially in the head protecting airbag device of the prior art, the front and rear ends of the inflator are individually inserted into the connection port portions. These connection port portions have to be sealed up by forcing them to contact with the outer circumference of the inflator. However, the inflator and the two connection port portions are connected in a straight line so that the inflating gas discharged in the axial direction of the inflator flows in the axial directions of the individual connection port portions. In other words, the connection port portions are easily pulled out from the end portions of the inflator if a pressure put on the individual connection port portions against the outer circumference of the inflator is low. This makes it necessary to connect the individual connection port portions and the inflator with great connection strength, including sealing properties. As a result, the head protecting airbag device of the prior art needs a large number of working-steps and thus high cost for assembly.